import java.util.Stack;

public class Solution {
    public boolean isValid(String s) {
        Stack<Character> stack = new Stack<>();

        for(int i = 0; i < s.length(); i++){
            char ch = s.charAt(i);
            if(ch == '(' || ch == '[' || ch == '{') {
                stack.push(ch);
            } else {
                if(stack.isEmpty()){
                    return false;
                }
                char ch2 = stack.peek();
                if(ch2 == '(' && ch == ')' || ch2 == '[' && ch == ']'
                        || ch2 == '{' && ch == '}'){

                    stack.pop();

                } else {
                    return false;
                }

            }
        }

        if(!stack.isEmpty()){
            return false;
        }
        return true;

    }
}
